Prognostic value of the C-reactive protein to albumin ratio in colorectal cancer: an updated systematic review and meta-analysis

Backgrounds The inflammatory biomarker "C-reactive protein to albumin ratio (CAR)" has been reported to significantly correlate to a variety of human cancers. However, there are conflicting results regarding the prognostic value of CAR in colorectal cancer. Previous studies mainly assessed patients in Eastern countries, so their findings may not be applicable to the Western population. Therefore, this updated meta-analysis aimed to investigate the prognostic value of pre-treatment CAR and outcomes of patients with colorectal cancer. Methods We conducted a systematic search for eligible literature until October 31, 2020, using PubMed and Embase databases. Studies assessing pre-treatment CAR and outcomes of colorectal cancer were included. Outcome measures included overall survival, disease-free survival, progression-free survival, and clinicopathological features. The pooled hazard ratios (HR) with 95% confidence intervals (CI) were used as effective values. Results A total of 15 studies involving 6329 patients were included in this study. The pooled results indicated that a high pre-treatment CAR was associated with poor overall survival (HR 2.028, 95% CI 1.808-2.275, p < 0.001) and poor disease-free survival/progression-free survival (HR 1.768, 95% CI 1.321-2.365, p < 0.001). Subgroup analysis revealed a constant prognostic value of the pre-treatment CAR despite different study regions, sample size, cancer stage, treatment methods, or the cut-off value used. We also noted a correlation between high pre-treatment CAR and old age, male sex, colon cancer, advanced stage (III/IV), large tumor size, poor differentiation, elevated carcinoembryonic antigen levels, neutrophil-to-lymphocyte ratio, and the modified Glasgow prognostic score. Conclusions High pre-treatment CAR was associated with poor overall survival, disease-free survival, and progression-free survival in colorectal cancer. It can serve as a prognostic marker for colorectal cancer in clinical practice.